Remote dose imaging from Cherenkov light using spatially resolved CT calibration in breast radiotherapy

Area of Science:

• Medical Physics
• Radiotherapy
• Medical Imaging

Background:

• Cherenkov light imaging offers real-time radiotherapy quality assurance by visualizing dose delivery.
• Tissue properties like hemoglobin, fat, water, and melanin attenuate and scatter Cherenkov light, affecting accuracy.
• Previous methods used bulk correction with computed tomography (CT) scans for attenuation.

Purpose of the Study:

• To develop and validate a pixel-by-pixel correction method for Cherenkov imaging using CT data.
• To improve the accuracy of real-time dose mapping in radiotherapy.
• To reduce inter- and intra-patient variations in Cherenkov light emission per unit dose.

Main Methods:

• Applied CT-derived radiodensity maps to correct spatial variations in Cherenkov image emissivity.
• Tested the technique on Cherenkov images from 13 post-lumpectomy breast cancer patients.
• Correlated Cherenkov light intensity with surface-rendered CT numbers to create a calibration curve.

Main Results:

• The pixel-by-pixel correction effectively suppressed variations in Cherenkov light emission per unit dose.
• The standard error of corrected Cherenkov intensity per unit dose was reduced by nearly half (from ~30% to ~17%).
• Demonstrated a significant improvement in the reliability of Cherenkov imaging.

Conclusions:

• Planning CT scans can effectively mitigate tissue-specific attenuation in Cherenkov images.
• This correction method allows Cherenkov images to be translated into more accurate near-surface dose images.
• The findings support the use of CT-corrected Cherenkov imaging for enhanced radiotherapy quality assurance.